Mechanical Oil Pressing of Linseed Oil
Mechanical oil pressing is to extract the oil from certain oil pressing machine from the oil material by physics pressure; all the courses are without any chemical additive. The typical oil pressing method usually includes the following two kinds, cold pressing, and hot pressing.
According to the heat and to extract more oil, the temperature should above 110 ℃, the oil pressing machine – hot press can get higher output, usually 10%-15% higher.
Most of the linseed oil is hot pressed oil in our daily life. Namely, linseeds were cleared and crushed, then heat them before pressing oil, it occurs a series of changes inside of oil raw materials: damage the oil materials cell, bring protein denaturation, reduce oil viscosity, etc, so that convenient to press oil and improve oil yield.
But the crude oil which was pressed through high-temperature treatment that color is a little darker, the acid value is higher, so it is not be cooking till refining. At the same time, it will lose a large number of physiological activator (vitamin E, sterol, carotenoid, etc.), bring about the waste of resources.
Hot pressing oil has pure flavor, especially sesame and peanut oil which contains abundant oil. The disadvantage is hot pressing oil maybe foam and swirl when frying things if not through treatment. But solve the problem is very easy. Whirlston Cooking Oil Press provide amphibious machine, hot and cold use, which is economical and practical.
The temperature should be controlled not higher than 90 ℃, in order to prevent the protein denaturation or other nutrition in the oil will be easier to refine. By using this oil pressing method, a certain oil pressing machine-cold press will be used.
With the development of the quality of life in recent years, people more and more like cold press oil about vegetable oil. As to cold press oil, you do not need heat oil raw materials; in the low-temperature condition, feed the oil raw materials to oil press. The temperature of the pressed oil is lower, the acid value is also lower. In this condition, the oil was not need refining, just through precipitating and filtering to get product oil.
Cold pressing oil with all natural, avoid the adverse effect of traditional high-temperature pressing. Cold pressing oil keeps the natural flavor and color of the oil raw materials, and also keeps physiological activator (vitamin E has an anti-aging function, sterol has skin care function and enhance human metabolism) of cooking oil. Cold pressing oil with flavor is the best choice of healthy life. But most of oil raw material is not suit to cold pressing, taking soybean, high erucic acid rapeseed, cottonseed, peanut, sesame as an example; soybean oil containing beany flavor, high erucic acid rapeseed oil containing biting taste, cottonseed containing toxin gossypol, deteriorating oil material containing aflatoxin, etc. They all need refining to remove the taste. However, as for sesame and peanut, must through hot pressing to get the flavor of sesame oil and fragrant peanut oil.
The oil raw materials must through handpicking, otherwise because of the distinction of oil raw material maturity and the influence of a harmful substance (for example, deteriorating oil material containing aflatoxin, cottonseed containing toxin gossypol, etc) inside oilseeds, that will affect cold pressing oil quality. In general, cooking oil which was cold pressed with a low smoke point, unstable moisture content, in favor of long-term storage. And also need crushing oilseeds so that improve oil yield. Sometimes have to be pressed twice, even the third time. The hot pressing method used for large size machinery pre-pressing, namely the first press oil. However, some manufacturers improving model press oil directly, do not need any other equipment.
As for the cold pressing machine, oil raw material does not need frying to press oil. The cooking oil has better light color, but oil tastes not sweet. Last but not least, cold pressing oil cannot foam and swirl when frying things.